This invention relates generally to waste heat boilers. More particularly, the present invention relates to apparatus for introducing hot gas into a heating surface tube of a waste heat boiler having an outer tube connected to the boiler wall, in particular to the tube plate, and having an inner or inlet tube that is connected to the outer tube by means of a rounded reversing cap to form an inlet port for the hot gas, which inner tube is surrounded by the outer tube at a distance and has an inflow section and an outflow section connected to the heating surface tube, and further having a coolant transport tube that is arranged between the outer tube and the inner tube and extends to the vicinity of the reversing cap.
In waste heat boilers or heat exchangers, hot gases (such as synthesis gases from partial oxidation systems) are cooled by coolants, in most cases generating steam in the process. The heat exchangers preferably consist of a plurality of straight, curved or helical heating surface systems that are connected to each other in parallel and that are composed of a plurality of heating surface tubes.
In waste heat boilers or heat exchangers designed with devices of this generic type for introducing hot gas into their heating surface tubes, it has become apparent that the geometric construction of the gas inlet is unfavorably designed with regard to real and potential corrosive attack and also with regard to the tendency of the gas inlet to clog during operation. Particularly the region of the transition from the conical inner or inlet tube to the subsequent straight or cylindrical inlet tube is subject to these problems. It has become apparent that the mechanisms described result in an extremely short service life of the components, brought about by a combined erosion and corrosion process, for example.
An apparatus of the generic type is known from the publication “Verfahrenstechnik: Anlagen-und Apparatebau, Komponenten und Teilkreisläufe” [Process Engineering: System and Apparatus Design, Components and Subcircuits] (1986), page 19, published by the firm of L. & C. Steinmüller. This known apparatus has an inlet or inner tube that narrows conically at a scanty 10° to the subsequent cylindrical innertube.
Additional generic devices for introducing hot gas into a heating surface tube of a waste gas boiler are known from the documents DE 198 22 546 C1 and DE 101 38 626 A1. The generic devices disclosed by these documents also have a conically narrowing inflow section and a straight cylindrical inflow section of the inlet or inner tube.